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[FFmpeg-devel,v5,08/12] avfilter/overlay_graphicsubs: Add overlay_graphicsubs and graphicsub2video filters

Message ID MN2PR04MB59812B30DF7EE4AED87EF776BAD89@MN2PR04MB5981.namprd04.prod.outlook.com
State New
Headers show
Series [FFmpeg-devel,v5,01/12] avutil/frame: Subtitle Filtering - Add AVMediaType property to AVFrame
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Context Check Description
andriy/configurex86 warning Failed to apply patch

Commit Message

Soft Works Sept. 12, 2021, 3:21 a.m. UTC
Signed-off-by: softworkz <softworkz@hotmail.com>
---
 doc/filters.texi                     | 104 ++++
 libavfilter/Makefile                 |   2 +
 libavfilter/allfilters.c             |   2 +
 libavfilter/vf_overlay_graphicsubs.c | 731 +++++++++++++++++++++++++++
 4 files changed, 839 insertions(+)
 create mode 100644 libavfilter/vf_overlay_graphicsubs.c

Comments

Andreas Rheinhardt Sept. 12, 2021, 8 p.m. UTC | #1
Soft Works:
> Signed-off-by: softworkz <softworkz@hotmail.com>
> ---
>  doc/filters.texi                     | 104 ++++
>  libavfilter/Makefile                 |   2 +
>  libavfilter/allfilters.c             |   2 +
>  libavfilter/vf_overlay_graphicsubs.c | 731 +++++++++++++++++++++++++++
>  4 files changed, 839 insertions(+)
>  create mode 100644 libavfilter/vf_overlay_graphicsubs.c
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 9ad6031d23..a6da018259 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -25016,6 +25016,110 @@ tools.
>  
>  @c man end VIDEO SINKS
>  
> +@chapter Subtitle Filters
> +@c man begin SUBTITLE FILTERS
> +
> +When you configure your FFmpeg build, you can disable any of the
> +existing filters using @code{--disable-filters}.
> +
> +Below is a description of the currently available subtitle filters.
> +
> +@section graphicsub2video
> +
> +Renders graphic subtitles as video frames. 
> +
> +This filter replaces the previous "sub2video" hack which did the conversion implicitly and up-front as subtitle filtering wasn't possible at that time.
> +To retain compatibility with earlier sub2video command lines, this filter is being auto-inserted in those cases.
> +
> +For overlaying graphicsal subtitles it is recommended to use the 'overlay_graphicsubs' filter which is more efficient and takes less processing resources.
> +
> +This filter is still useful in cases where the overlay is done with hardware acceleration (e.g. overlay_qsv, overlay_vaapi, overlay_cuda) for preparing the overlay frames.
> +
> +It accepts the following parameters:
> +
> +@table @option
> +@item size, s
> +Set the size of the output video frame.
> +
> +@end table
> +
> +@subsection Examples
> +
> +@itemize
> +@item
> +Overlay PGS subtitles
> +(not recommended - better use overlay_graphicsubs)
> +@example
> +ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:1]graphicsub2video[subs];[0:0][subs]overlay" output.mp4
> +@end example
> +
> +@item
> +Overlay PGS subtitles implicitly 
> +The graphicsub2video is inserted automatically for compatibility with legacy command lines. 
> +@example
> +ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:0][0:1]overlay" output.mp4
> +@end example
> +@end itemize
> +
> +@section overlay_graphicsubs
> +
> +Overlay graphic subtitles onto a video stream.
> +
> +This filter can blend graphical subtitles on a video stream directly, i.e. without creating full-size alpha images first.
> +The blending operation is limited to the area of the subtitle rectangles, which also means that no processing is done at times where no subtitles are to be displayed.
> +
> +
> +It accepts the following parameters:
> +
> +@table @option
> +@item x
> +@item y
> +Set the expression for the x and y coordinates of the overlaid video
> +on the main video. Default value is "0" for both expressions. In case
> +the expression is invalid, it is set to a huge value (meaning that the
> +overlay will not be displayed within the output visible area).
> +
> +@item eof_action
> +See @ref{framesync}.
> +
> +@item eval
> +Set when the expressions for @option{x}, and @option{y} are evaluated.
> +
> +It accepts the following values:
> +@table @samp
> +@item init
> +only evaluate expressions once during the filter initialization or
> +when a command is processed
> +
> +@item frame
> +evaluate expressions for each incoming frame
> +@end table
> +
> +Default value is @samp{frame}.
> +
> +@item shortest
> +See @ref{framesync}.
> +
> +@end table
> +
> +@subsection Examples
> +
> +@itemize
> +@item
> +Overlay PGS subtitles
> +@example
> +ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:1]graphicsub2video[subs];[0:0][subs]overlay" output.mp4
> +@end example
> +
> +@item
> +Overlay PGS subtitles implicitly 
> +The graphicsub2video is inserted automatically for compatibility with legacy command lines. 
> +@example
> +ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:0][0:1]overlay" output.mp4
> +@end example
> +@end itemize
> +@c man end SUBTITLE FILTERS
> +
>  @chapter Multimedia Filters
>  @c man begin MULTIMEDIA FILTERS
>  
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index a510dd12b4..f9b33d4ead 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -289,6 +289,7 @@ OBJS-$(CONFIG_FSPP_FILTER)                   += vf_fspp.o qp_table.o
>  OBJS-$(CONFIG_GBLUR_FILTER)                  += vf_gblur.o
>  OBJS-$(CONFIG_GEQ_FILTER)                    += vf_geq.o
>  OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
> +OBJS-$(CONFIG_GRAPHICSUB2VIDEO_FILTER)       += vf_overlay_graphicsubs.o framesync.o
>  OBJS-$(CONFIG_GRAPHMONITOR_FILTER)           += f_graphmonitor.o
>  OBJS-$(CONFIG_GRAYWORLD_FILTER)              += vf_grayworld.o
>  OBJS-$(CONFIG_GREYEDGE_FILTER)               += vf_colorconstancy.o
> @@ -362,6 +363,7 @@ OBJS-$(CONFIG_OVERLAY_CUDA_FILTER)           += vf_overlay_cuda.o framesync.o vf
>  OBJS-$(CONFIG_OVERLAY_OPENCL_FILTER)         += vf_overlay_opencl.o opencl.o \
>                                                  opencl/overlay.o framesync.o
>  OBJS-$(CONFIG_OVERLAY_QSV_FILTER)            += vf_overlay_qsv.o framesync.o
> +OBJS-$(CONFIG_OVERLAY_GRAPHICSUBS_FILTER)    += vf_overlay_graphicsubs.o framesync.o
>  OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o vulkan.o
>  OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
>  OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index b27ef6f027..ca983db5b4 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -344,6 +344,7 @@ extern const AVFilter ff_vf_oscilloscope;
>  extern const AVFilter ff_vf_overlay;
>  extern const AVFilter ff_vf_overlay_opencl;
>  extern const AVFilter ff_vf_overlay_qsv;
> +extern const AVFilter ff_vf_overlay_graphicsubs;
>  extern const AVFilter ff_vf_overlay_vulkan;
>  extern const AVFilter ff_vf_overlay_cuda;
>  extern const AVFilter ff_vf_owdenoise;
> @@ -522,6 +523,7 @@ extern const AVFilter ff_avf_showvolume;
>  extern const AVFilter ff_avf_showwaves;
>  extern const AVFilter ff_avf_showwavespic;
>  extern const AVFilter ff_vaf_spectrumsynth;
> +extern const AVFilter ff_svf_graphicsub2video;
>  
>  /* multimedia sources */
>  extern const AVFilter ff_avsrc_amovie;
> diff --git a/libavfilter/vf_overlay_graphicsubs.c b/libavfilter/vf_overlay_graphicsubs.c
> new file mode 100644
> index 0000000000..15c07c9bc4
> --- /dev/null
> +++ b/libavfilter/vf_overlay_graphicsubs.c
> @@ -0,0 +1,731 @@
> +/*
> + * Copyright (c) 2021 softworkz
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * overlay graphical subtitles on top of a video frame
> + */
> +
> +#include "avfilter.h"
> +#include "formats.h"
> +#include "libavutil/common.h"
> +#include "libavutil/eval.h"
> +#include "libavutil/avstring.h"
> +#include "libavutil/pixdesc.h"
> +#include "libavutil/imgutils.h"
> +#include "libavutil/opt.h"
> +#include "internal.h"
> +#include "drawutils.h"
> +#include "framesync.h"
> +
> +#include "libavcodec/avcodec.h"
> +
> +enum var_name {
> +    VAR_MAIN_W,    VAR_MW,
> +    VAR_MAIN_H,    VAR_MH,
> +    VAR_OVERLAY_W, VAR_OW,
> +    VAR_OVERLAY_H, VAR_OH,
> +    VAR_HSUB,
> +    VAR_VSUB,
> +    VAR_X,
> +    VAR_Y,
> +    VAR_N,
> +    VAR_POS,
> +    VAR_T,
> +    VAR_VARS_NB
> +};
> +
> +typedef struct OverlaySubsContext {
> +    const AVClass *class;
> +    int x, y;                   ///< position of overlaid picture
> +    int w, h;
> +    AVFrame *outpicref;
> +
> +    int main_is_packed_rgb;
> +    uint8_t main_rgba_map[4];
> +    int main_has_alpha;
> +    uint8_t overlay_rgba_map[4];
> +    int eval_mode;              ///< EvalMode
> +
> +    FFFrameSync fs;
> +
> +    int main_pix_step[4];       ///< steps per pixel for each plane of the main output
> +    int hsub, vsub;             ///< chroma subsampling values
> +    const AVPixFmtDescriptor *main_desc; ///< format descriptor for main input
> +
> +    double var_values[VAR_VARS_NB];
> +    char *x_expr, *y_expr;
> +
> +    AVExpr *x_pexpr, *y_pexpr;
> +} OverlaySubsContext;
> +
> +static const char *const var_names[] = {
> +    "main_w",    "W", ///< width  of the main    video
> +    "main_h",    "H", ///< height of the main    video
> +    "overlay_w", "w", ///< width  of the overlay video
> +    "overlay_h", "h", ///< height of the overlay video
> +    "hsub",
> +    "vsub",
> +    "x",
> +    "y",
> +    "n",            ///< number of frame
> +    "pos",          ///< position in the file
> +    "t",            ///< timestamp expressed in seconds
> +    NULL
> +};
> +
> +#define MAIN    0
> +#define OVERLAY 1
> +
> +#define R 0
> +#define G 1
> +#define B 2
> +#define A 3
> +
> +#define Y 0
> +#define U 1
> +#define V 2
> +
> +enum EvalMode {
> +    EVAL_MODE_INIT,
> +    EVAL_MODE_FRAME,
> +    EVAL_MODE_NB
> +};
> +
> +static av_cold void overlay_graphicsubs_uninit(AVFilterContext *ctx)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +
> +    ff_framesync_uninit(&s->fs);
> +    av_expr_free(s->x_pexpr); s->x_pexpr = NULL;
> +    av_expr_free(s->y_pexpr); s->y_pexpr = NULL;
> +}
> +
> +static inline int normalize_xy(double d, int chroma_sub)
> +{
> +    if (isnan(d))
> +        return INT_MAX;
> +    return (int)d & ~((1 << chroma_sub) - 1);
> +}
> +
> +static void eval_expr(AVFilterContext *ctx)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +
> +    s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
> +    s->var_values[VAR_Y] = av_expr_eval(s->y_pexpr, s->var_values, NULL);
> +    /* It is necessary if x is expressed from y  */
> +    s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
> +    s->x = normalize_xy(s->var_values[VAR_X], s->hsub);
> +    s->y = normalize_xy(s->var_values[VAR_Y], s->vsub);
> +}
> +
> +static int set_expr(AVExpr **pexpr, const char *expr, const char *option, void *log_ctx)
> +{
> +    int ret;
> +    AVExpr *old = NULL;
> +
> +    if (*pexpr)
> +        old = *pexpr;
> +    ret = av_expr_parse(pexpr, expr, var_names,
> +                        NULL, NULL, NULL, NULL, 0, log_ctx);
> +    if (ret < 0) {
> +        av_log(log_ctx, AV_LOG_ERROR,
> +               "Error when evaluating the expression '%s' for %s\n",
> +               expr, option);
> +        *pexpr = old;
> +        return ret;
> +    }
> +
> +    av_expr_free(old);
> +    return 0;
> +}
> +
> +static int overlay_graphicsubs_query_formats(AVFilterContext *ctx)
> +{
> +    AVFilterFormats *formats;
> +    AVFilterLink *inlink0 = ctx->inputs[0];
> +    AVFilterLink *inlink1 = ctx->inputs[1];
> +    AVFilterLink *outlink = ctx->outputs[0];
> +    int ret;
> +    static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_BITMAP, AV_SUBTITLE_FMT_NONE };
> +    static const enum AVPixelFormat supported_pix_fmts[] = {
> +        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV444P,
> +        AV_PIX_FMT_ARGB,  AV_PIX_FMT_RGBA,
> +        AV_PIX_FMT_ABGR,  AV_PIX_FMT_BGRA,
> +        AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
> +        AV_PIX_FMT_NONE
> +    };
> +
> +    /* set input0 video formats */
> +    formats = ff_make_format_list(supported_pix_fmts);
> +    if ((ret = ff_formats_ref(formats, &inlink0->outcfg.formats)) < 0)
> +        return ret;
> +
> +    /* set input1 subtitle formats */
> +    formats = ff_make_format_list(subtitle_fmts);
> +    if ((ret = ff_formats_ref(formats, &inlink1->outcfg.formats)) < 0)
> +        return ret;
> +
> +    /* set output0 video formats */
> +    formats = ff_make_format_list(supported_pix_fmts);
> +    if ((ret = ff_formats_ref(formats, &outlink->incfg.formats)) < 0)
> +        return ret;
> +
> +    return 0;
> +}
> +
> +static int config_output(AVFilterLink *outlink)
> +{
> +    AVFilterContext *ctx = outlink->src;
> +    OverlaySubsContext *s = ctx->priv;
> +    int ret;
> +
> +    if ((ret = ff_framesync_init_dualinput(&s->fs, ctx)) < 0)
> +        return ret;
> +
> +    outlink->w = ctx->inputs[MAIN]->w;
> +    outlink->h = ctx->inputs[MAIN]->h;
> +    outlink->time_base = ctx->inputs[MAIN]->time_base;
> +
> +    return ff_framesync_configure(&s->fs);
> +}
> +
> +// divide by 255 and round to nearest
> +// apply a fast variant: (X+127)/255 = ((X+127)*257+257)>>16 = ((X+128)*257)>>16
> +#define FAST_DIV255(x) ((((x) + 128) * 257) >> 16)
> +
> +// calculate the non-pre-multiplied alpha, applying the general equation:
> +// alpha = alpha_overlay / ( (alpha_main + alpha_overlay) - (alpha_main * alpha_overlay) )
> +// (((x) << 16) - ((x) << 9) + (x)) is a faster version of: 255 * 255 * x
> +// ((((x) + (y)) << 8) - ((x) + (y)) - (y) * (x)) is a faster version of: 255 * (x + y)
> +#define UNPREMULTIPLY_ALPHA(x, y) ((((x) << 16) - ((x) << 9) + (x)) / ((((x) + (y)) << 8) - ((x) + (y)) - (y) * (x)))
> +
> +/**
> + * Blend image in src to destination buffer dst at position (x, y).
> + */
> +static av_always_inline void blend_packed_rgb(const AVFilterContext *ctx,
> +    const AVFrame *dst, const AVSubtitleRect *src,
> +    int x, int y,
> +    int is_straight)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +    int i, imax, j, jmax;
> +    const int src_w = src->w;
> +    const int src_h = src->h;
> +    const int dst_w = dst->width;
> +    const int dst_h = dst->height;
> +    uint8_t alpha;          ///< the amount of overlay to blend on to main
> +    const int dr = s->main_rgba_map[R];
> +    const int dg = s->main_rgba_map[G];
> +    const int db = s->main_rgba_map[B];
> +    const int da = s->main_rgba_map[A];
> +    const int dstep = s->main_pix_step[0];
> +    const int sr = s->overlay_rgba_map[R];
> +    const int sg = s->overlay_rgba_map[G];
> +    const int sb = s->overlay_rgba_map[B];
> +    const int sa = s->overlay_rgba_map[A];
> +    uint32_t *pal = (uint32_t *)src->data[1];
> +    int slice_start, slice_end;
> +    uint8_t *S, *sp, *d, *dp;
> +
> +    i = FFMAX(-y, 0);
> +    imax = FFMIN3(-y + dst_h, FFMIN(src_h, dst_h), y + src_h);
> +
> +    slice_start = i;
> +    slice_end = i + imax;
> +
> +    sp = src->data[0] + slice_start       * src->linesize[0];
> +    dp = dst->data[0] + (slice_start + y) * dst->linesize[0];
> +
> +    for (i = slice_start; i < slice_end; i++) {
> +        j = FFMAX(-x, 0);
> +        S = sp + j;
> +        d = dp + ((x + j) * dstep);
> +
> +        for (jmax = FFMIN(-x + dst_w, src_w); j < jmax; j++) {
> +            uint32_t val = pal[*S];
> +            const uint8_t *sval = (uint8_t *)&val;
> +            alpha = sval[sa];
> +
> +            // if the main channel has an alpha channel, alpha has to be calculated
> +            // to create an un-premultiplied (straight) alpha value
> +            if (s->main_has_alpha && alpha != 0 && alpha != 255) {
> +                const uint8_t alpha_d = d[da];
> +                alpha = UNPREMULTIPLY_ALPHA(alpha, alpha_d);
> +            }
> +
> +            switch (alpha) {
> +            case 0:
> +                break;
> +            case 255:
> +                d[dr] = sval[sr];
> +                d[dg] = sval[sg];
> +                d[db] = sval[sb];
> +                break;
> +            default:
> +                // main_value = main_value * (1 - alpha) + overlay_value * alpha
> +                // since alpha is in the range 0-255, the result must divided by 255
> +                d[dr] = is_straight ? FAST_DIV255(d[dr] * (255 - alpha) + sval[sr] * alpha) :
> +                        FFMIN(FAST_DIV255(d[dr] * (255 - alpha)) + sval[sr], 255);
> +                d[dg] = is_straight ? FAST_DIV255(d[dg] * (255 - alpha) + sval[sg] * alpha) :
> +                        FFMIN(FAST_DIV255(d[dg] * (255 - alpha)) + sval[sg], 255);
> +                d[db] = is_straight ? FAST_DIV255(d[db] * (255 - alpha) + sval[sb] * alpha) :
> +                        FFMIN(FAST_DIV255(d[db] * (255 - alpha)) + sval[sb], 255);
> +            }
> +
> +            if (s->main_has_alpha) {
> +                switch (alpha) {
> +                case 0:
> +                    break;
> +                case 255:
> +                    d[da] = sval[sa];
> +                    break;
> +                default:
> +                    // apply alpha compositing: main_alpha += (1-main_alpha) * overlay_alpha
> +                    d[da] += FAST_DIV255((255 - d[da]) * S[sa]);
> +                }
> +            }
> +            d += dstep;
> +            S += 1;
> +        }
> +        dp += dst->linesize[0];
> +        sp += src->linesize[0];
> +    }
> +}
> +
> +static av_always_inline void blend_plane_8_8bits(const AVFilterContext *ctx, const AVFrame *dst, const AVSubtitleRect *src,
> +    const uint32_t *yuv_pal, int src_w, int src_h, int dst_w, int dst_h, int plane, int hsub, int vsub,
> +    int x, int y, int dst_plane, int dst_offset, int dst_step)
> +{
> +    const int src_wp = AV_CEIL_RSHIFT(src_w, hsub);
> +    const int src_hp = AV_CEIL_RSHIFT(src_h, vsub);
> +    const int dst_wp = AV_CEIL_RSHIFT(dst_w, hsub);
> +    const int dst_hp = AV_CEIL_RSHIFT(dst_h, vsub);
> +    const int yp = y >> vsub;
> +    const int xp = x >> hsub;
> +    uint8_t *s, *sp, *d, *dp, *dap;
> +    int imax, i, j, jmax;
> +    int slice_start, slice_end;
> +
> +    i = FFMAX(-yp, 0);                                                                                     \
> +    imax = FFMIN3(-yp + dst_hp, FFMIN(src_hp, dst_hp), yp + src_hp);                                       \
> +
> +    slice_start = i;
> +    slice_end = i + imax;
> +
> +    sp = src->data[0] + (slice_start << vsub) * src->linesize[0];
> +    dp = dst->data[dst_plane] + (yp + slice_start) * dst->linesize[dst_plane] + dst_offset;
> +
> +    dap = dst->data[3] + ((yp + slice_start) << vsub) * dst->linesize[3];
> +
> +    for (i = slice_start; i < slice_end; i++) {
> +        j = FFMAX(-xp, 0);
> +        d = dp + (xp + j) * dst_step;
> +        s = sp + (j << hsub);
> +        jmax = FFMIN(-xp + dst_wp, src_wp);    
> +
> +        for (; j < jmax; j++) {
> +            uint32_t val = yuv_pal[*s];
> +            const uint8_t *sval = (uint8_t *)&val;
> +            const int alpha = sval[3];
> +            const int max = 255, mid = 128;
> +            const int d_int = *d;
> +            const int sval_int = sval[plane];
> +
> +            switch (alpha) {
> +            case 0:
> +                break;
> +            case 255:
> +                *d = sval[plane];
> +                break;
> +            default:
> +                if (plane > 0)
> +                    *d = av_clip(FAST_DIV255((d_int - mid) * (max - alpha) + (sval_int - mid) * alpha) , -mid, mid) + mid;
> +                else
> +                    *d = FAST_DIV255(d_int * (max - alpha) + sval_int * alpha);
> +                break;
> +            }
> +
> +            d += dst_step;
> +            s += 1 << hsub;
> +        }
> +        dp += dst->linesize[dst_plane];
> +        sp +=  (1 << vsub) * src->linesize[0];
> +        dap += (1 << vsub) * dst->linesize[3];
> +    }
> +}
> +
> +#define RGB2Y(r, g, b) (uint8_t)(((66 * (r) + 129 * (g) +  25 * (b) + 128) >> 8) +  16)
> +#define RGB2U(r, g, b) (uint8_t)(((-38 * (r) - 74 * (g) + 112 * (b) + 128) >> 8) + 128)
> +#define RGB2V(r, g, b) (uint8_t)(((112 * (r) - 94 * (g) -  18 * (b) + 128) >> 8) + 128)
> +/* Converts R8 G8 B8 color to YUV. */
> +static av_always_inline void rgb_2_yuv(uint8_t r, uint8_t g, uint8_t b, uint8_t* y, uint8_t* u, uint8_t* v)
> +{
> +    *y = RGB2Y((int)r, (int)g, (int)b);
> +    *u = RGB2U((int)r, (int)g, (int)b);
> +    *v = RGB2V((int)r, (int)g, (int)b);
> +}
> +
> +
> +static av_always_inline void blend_yuv_8_8bits(AVFilterContext *ctx, AVFrame *dst, const AVSubtitleRect *src, int hsub, int vsub, int x, int y)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +    const int src_w = src->w;
> +    const int src_h = src->h;
> +    const int dst_w = dst->width;
> +    const int dst_h = dst->height;
> +    const int sr = s->overlay_rgba_map[R];
> +    const int sg = s->overlay_rgba_map[G];
> +    const int sb = s->overlay_rgba_map[B];
> +    const int sa = s->overlay_rgba_map[A];
> +    uint32_t *pal = (uint32_t *)src->data[1];
> +    uint32_t yuvpal[256];
> +
> +    for (int i = 0; i < 256; ++i) {
> +        const uint8_t *rgba = (uint8_t *)&pal[i];
> +        uint8_t *yuva = (uint8_t *)&yuvpal[i];
> +        rgb_2_yuv(rgba[sr], rgba[sg], rgba[sb], &yuva[Y], &yuva[U], &yuva[V]);
> +        yuva[3] = rgba[sa];
> +    }
> +
> +    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, Y, 0,    0,    x, y, s->main_desc->comp[Y].plane, s->main_desc->comp[Y].offset, s->main_desc->comp[Y].step);
> +    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, U, hsub, vsub, x, y, s->main_desc->comp[U].plane, s->main_desc->comp[U].offset, s->main_desc->comp[U].step);
> +    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, V, hsub, vsub, x, y, s->main_desc->comp[V].plane, s->main_desc->comp[V].offset, s->main_desc->comp[V].step);
> +}
> +
> +static int config_input_main(AVFilterLink *inlink)
> +{
> +    int ret;
> +    AVFilterContext *ctx  = inlink->dst;
> +    OverlaySubsContext *s = inlink->dst->priv;
> +    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
> +
> +    av_image_fill_max_pixsteps(s->main_pix_step,    NULL, pix_desc);
> +    ff_fill_rgba_map(s->overlay_rgba_map, AV_PIX_FMT_RGB32); // it's actually AV_PIX_FMT_PAL8);
> +
> +    s->hsub = pix_desc->log2_chroma_w;
> +    s->vsub = pix_desc->log2_chroma_h;
> +
> +    s->main_desc = pix_desc;
> +
> +    s->main_is_packed_rgb = ff_fill_rgba_map(s->main_rgba_map, inlink->format) >= 0;
> +    s->main_has_alpha = !(pix_desc->flags & AV_PIX_FMT_FLAG_ALPHA);
> +
> +    /* Finish the configuration by evaluating the expressions
> +       now when both inputs are configured. */
> +    s->var_values[VAR_MAIN_W   ] = s->var_values[VAR_MW] = ctx->inputs[MAIN   ]->w;
> +    s->var_values[VAR_MAIN_H   ] = s->var_values[VAR_MH] = ctx->inputs[MAIN   ]->h;
> +    s->var_values[VAR_OVERLAY_W] = s->var_values[VAR_OW] = ctx->inputs[OVERLAY]->w;
> +    s->var_values[VAR_OVERLAY_H] = s->var_values[VAR_OH] = ctx->inputs[OVERLAY]->h;
> +    s->var_values[VAR_HSUB]  = 1<<pix_desc->log2_chroma_w;
> +    s->var_values[VAR_VSUB]  = 1<<pix_desc->log2_chroma_h;
> +    s->var_values[VAR_X]     = NAN;
> +    s->var_values[VAR_Y]     = NAN;
> +    s->var_values[VAR_N]     = 0;
> +    s->var_values[VAR_T]     = NAN;
> +    s->var_values[VAR_POS]   = NAN;
> +
> +    if ((ret = set_expr(&s->x_pexpr,      s->x_expr,      "x",      ctx)) < 0 ||
> +        (ret = set_expr(&s->y_pexpr,      s->y_expr,      "y",      ctx)) < 0)
> +        return ret;
> +
> +    if (s->eval_mode == EVAL_MODE_INIT) {
> +        eval_expr(ctx);
> +        av_log(ctx, AV_LOG_VERBOSE, "x:%f xi:%d y:%f yi:%d\n",
> +               s->var_values[VAR_X], s->x,
> +               s->var_values[VAR_Y], s->y);
> +    }
> +
> +    av_log(ctx, AV_LOG_VERBOSE,
> +           "main w:%d h:%d fmt:%s overlay w:%d h:%d fmt:%s\n",
> +           ctx->inputs[MAIN]->w, ctx->inputs[MAIN]->h,
> +           av_get_pix_fmt_name(ctx->inputs[MAIN]->format),
> +           ctx->inputs[OVERLAY]->w, ctx->inputs[OVERLAY]->h,
> +           av_get_pix_fmt_name(ctx->inputs[OVERLAY]->format));
> +    return 0;
> +}
> +
> +static int do_blend(FFFrameSync *fs)
> +{
> +    AVFilterContext *ctx = fs->parent;
> +    AVFrame *mainpic, *second;
> +    OverlaySubsContext *s = ctx->priv;
> +    AVFilterLink *inlink = ctx->inputs[0];
> +    unsigned num_rects, i;
> +    int ret;
> +
> +    ret = ff_framesync_dualinput_get_writable(fs, &mainpic, &second);
> +    if (ret < 0)
> +        return ret;
> +    if (!second)
> +        return ff_filter_frame(ctx->outputs[0], mainpic);
> +
> +    if (s->eval_mode == EVAL_MODE_FRAME) {
> +        int64_t pos = mainpic->pkt_pos;
> +
> +        s->var_values[VAR_N] = inlink->frame_count_out;
> +        s->var_values[VAR_T] = mainpic->pts == AV_NOPTS_VALUE ?
> +            NAN : mainpic->pts * av_q2d(inlink->time_base);
> +        s->var_values[VAR_POS] = pos == -1 ? NAN : pos;
> +
> +        s->var_values[VAR_OVERLAY_W] = s->var_values[VAR_OW] = second->width;
> +        s->var_values[VAR_OVERLAY_H] = s->var_values[VAR_OH] = second->height;
> +        s->var_values[VAR_MAIN_W   ] = s->var_values[VAR_MW] = mainpic->width;
> +        s->var_values[VAR_MAIN_H   ] = s->var_values[VAR_MH] = mainpic->height;
> +
> +        eval_expr(ctx);
> +        av_log(ctx, AV_LOG_DEBUG, "n:%f t:%f pos:%f x:%f xi:%d y:%f yi:%d\n",
> +               s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
> +               s->var_values[VAR_X], s->x,
> +               s->var_values[VAR_Y], s->y);
> +    }
> +
> +    num_rects = second->num_subtitle_rects > 1 ? 1 : second->num_subtitle_rects;
> +
> +    for (i = 0; i < num_rects; i++) {
> +        const AVSubtitleRect  *sub_rect = second->subtitle_rects[i];
> +
> +        if (sub_rect->type != AV_SUBTITLE_FMT_BITMAP) {
> +            av_log(NULL, AV_LOG_WARNING, "sub2video: non-bitmap subtitle\n");
> +            return AVERROR_INVALIDDATA;
> +        }
> +
> +        switch (inlink->format) {
> +        case AV_PIX_FMT_YUV420P:
> +            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 1, 1, sub_rect->x + s->x, sub_rect->y + s->y);
> +            break;
> +        case AV_PIX_FMT_YUV422P:
> +            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 1, 0, sub_rect->x + s->x, sub_rect->y + s->y);
> +            break;
> +        case AV_PIX_FMT_YUV444P:
> +            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 0, 0, sub_rect->x + s->x, sub_rect->y + s->y);
> +            break;
> +        case AV_PIX_FMT_RGB24:
> +        case AV_PIX_FMT_BGR24:
> +        case AV_PIX_FMT_ARGB:
> +        case AV_PIX_FMT_RGBA:
> +        case AV_PIX_FMT_BGRA:
> +        case AV_PIX_FMT_ABGR:
> +            blend_packed_rgb(ctx, mainpic, sub_rect, sub_rect->x + s->x, sub_rect->y + s->y, 1);
> +            break;
> +        default:
> +            av_assert0(0);
> +            break;
> +        }
> +    }
> +
> +    return ff_filter_frame(ctx->outputs[0], mainpic);
> +}
> +
> +static av_cold int overlay_graphicsubs_init(AVFilterContext *ctx)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +
> +    s->fs.on_event = do_blend;
> +    return 0;
> +}
> +
> +static int overlay_graphicsubs_activate(AVFilterContext *ctx)
> +{
> +    OverlaySubsContext *s = ctx->priv;
> +    return ff_framesync_activate(&s->fs);
> +}
> +
> +static int graphicsub2video_query_formats(AVFilterContext *ctx)
> +{
> +    AVFilterFormats *formats;
> +    AVFilterLink *inlink = ctx->inputs[0];
> +    AVFilterLink *outlink = ctx->outputs[0];
> +    static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_BITMAP, AV_SUBTITLE_FMT_NONE };
> +    static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_RGB32, AV_PIX_FMT_NONE };
> +    int ret;
> +
> +    /* set input subtitle formats */
> +    formats = ff_make_format_list(subtitle_fmts);
> +    if ((ret = ff_formats_ref(formats, &inlink->outcfg.formats)) < 0)
> +        return ret;
> +
> +    /* set output video formats */
> +    formats = ff_make_format_list(pix_fmts);
> +    if ((ret = ff_formats_ref(formats, &outlink->incfg.formats)) < 0)
> +        return ret;
> +
> +    return 0;
> +}
> +
> +static int graphicsub2video_config_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    OverlaySubsContext *s = ctx->priv;
> +
> +    if (s->w <= 0 || s->h <= 0) {
> +        s->w = inlink->w;
> +        s->h = inlink->h;
> +    }
> +    return 0;
> +}
> +
> +static int graphicsub2video_config_output(AVFilterLink *outlink)
> +{
> +    const AVFilterContext *ctx  = outlink->src;
> +    OverlaySubsContext *s = ctx->priv;
> +    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(outlink->format);
> +
> +    outlink->w = s->w;
> +    outlink->h = s->h;
> +    outlink->sample_aspect_ratio = (AVRational){1,1};
> +
> +    av_image_fill_max_pixsteps(s->main_pix_step, NULL, pix_desc);
> +    ff_fill_rgba_map(s->overlay_rgba_map, AV_PIX_FMT_RGB32);
> +
> +    s->hsub = pix_desc->log2_chroma_w;
> +    s->vsub = pix_desc->log2_chroma_h;
> +
> +    s->main_desc = pix_desc;
> +
> +    s->main_is_packed_rgb = ff_fill_rgba_map(s->main_rgba_map, outlink->format) >= 0;
> +    s->main_has_alpha = !(pix_desc->flags & AV_PIX_FMT_FLAG_ALPHA);
> +
> +    return 0;
> +}
> +
> +static int graphicsub2video_filter_frame(AVFilterLink *inlink, AVFrame *src_frame)
> +{
> +    AVFilterLink *outlink = inlink->dst->outputs[0];
> +    AVFrame *out;
> +    const unsigned num_rects = src_frame->num_subtitle_rects;
> +    unsigned int i;
> +
> +    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
> +    if (!out)
> +        return AVERROR(ENOMEM);
> +
> +    memset(out->data[0], 0, out->linesize[0] * out->height);
> +
> +    out->pts = src_frame->pts;
> +
> +
> +    for (i = 0; i < num_rects; i++) {
> +        const AVSubtitleRect  *sub_rect = src_frame->subtitle_rects[i];
> +
> +        if (sub_rect->type != AV_SUBTITLE_FMT_BITMAP) {
> +            av_log(NULL, AV_LOG_WARNING, "sub2video: non-bitmap subtitle\n");
> +            return AVERROR_INVALIDDATA;
> +        }
> +
> +        blend_packed_rgb(inlink->dst, out, sub_rect, sub_rect->x, sub_rect->y, 1);
> +    }
> +
> +    av_frame_free(&src_frame);
> +    return ff_filter_frame(outlink, out);
> +}
> +
> +#define OFFSET(x) offsetof(OverlaySubsContext, x)
> +#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
> +
> +static const AVOption overlay_graphicsubs_options[] = {
> +    { "x", "set the x expression", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
> +    { "y", "set the y expression", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
> +    { "eof_action", "Action to take when encountering EOF from secondary input ",
> +        OFFSET(fs.opt_eof_action), AV_OPT_TYPE_INT, { .i64 = EOF_ACTION_REPEAT },
> +        EOF_ACTION_REPEAT, EOF_ACTION_PASS, .flags = FLAGS, "eof_action" },
> +        { "repeat", "Repeat the previous frame.",   0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_REPEAT }, .flags = FLAGS, "eof_action" },
> +        { "endall", "End both streams.",            0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_ENDALL }, .flags = FLAGS, "eof_action" },
> +        { "pass",   "Pass through the main input.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS },   .flags = FLAGS, "eof_action" },
> +    { "eval", "specify when to evaluate expressions", OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_FRAME}, 0, EVAL_MODE_NB-1, FLAGS, "eval" },
> +         { "init",  "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit = "eval" },
> +         { "frame", "eval expressions per-frame",                  0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },
> +    { "shortest", "force termination when the shortest input terminates", OFFSET(fs.opt_shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
> +    { "repeatlast", "repeat overlay of the last overlay frame", OFFSET(fs.opt_repeatlast), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },

Why are you duplicating framesync options? They are already accessible
(that's what the preinit and the child_next/child_class_next stuff is for).

> +    { NULL }
> +};
> +
> +static const AVOption graphicsub2video_options[] = {
> +    { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, FLAGS },
> +    { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, FLAGS },
> +    { NULL }
> +};
> +
> +FRAMESYNC_DEFINE_CLASS(overlay_graphicsubs, OverlaySubsContext, fs);
> +
> +static const AVFilterPad overlay_graphicsubs_inputs[] = {
> +    {
> +        .name         = "main",
> +        .type         = AVMEDIA_TYPE_VIDEO,
> +        .config_props = config_input_main,
> +        .flags        = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
> +    },
> +    {
> +        .name         = "overlay",
> +        .type         = AVMEDIA_TYPE_SUBTITLE,
> +    },
> +};
> +
> +static const AVFilterPad overlay_graphicsubs_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_VIDEO,
> +        .config_props  = config_output,
> +    },
> +};
> +
> +const AVFilter ff_vf_overlay_graphicsubs = {
> +    .name          = "overlay_graphicsubs",
> +    .description   = NULL_IF_CONFIG_SMALL("Overlay graphical subtitles on top of the input."),
> +    .preinit       = overlay_graphicsubs_framesync_preinit,
> +    .init          = overlay_graphicsubs_init,
> +    .uninit        = overlay_graphicsubs_uninit,
> +    .priv_size     = sizeof(OverlaySubsContext),
> +    .priv_class    = &overlay_graphicsubs_class,
> +    .query_formats = overlay_graphicsubs_query_formats,
> +    .activate      = overlay_graphicsubs_activate,
> +    FILTER_INPUTS(overlay_graphicsubs_inputs),
> +    FILTER_OUTPUTS(overlay_graphicsubs_outputs),
> +};
> +
> +AVFILTER_DEFINE_CLASS(graphicsub2video);
> +
> +static const AVFilterPad graphicsub2video_inputs[] = {
> +    {
> +        .name         = "default",
> +        .type         = AVMEDIA_TYPE_SUBTITLE,
> +        .filter_frame = graphicsub2video_filter_frame,
> +        .config_props = graphicsub2video_config_input,
> +    },
> +};
> +
> +static const AVFilterPad graphicsub2video_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_VIDEO,
> +        .config_props  = graphicsub2video_config_output,
> +    },
> +};
> +
> +AVFilter ff_svf_graphicsub2video = {
> +    .name          = "graphicsub2video",
> +    .description   = NULL_IF_CONFIG_SMALL("Convert graphical subtitles to video"),
> +    .query_formats = graphicsub2video_query_formats,
> +    .priv_size     = sizeof(OverlaySubsContext),
> +    .priv_class    = &graphicsub2video_class,
> +    FILTER_INPUTS(graphicsub2video_inputs),
> +    FILTER_OUTPUTS(graphicsub2video_outputs),
> +};
>
Soft Works Sept. 15, 2021, 9:07 a.m. UTC | #2
> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Andreas Rheinhardt
> Sent: Sunday, 12 September 2021 22:00
> To: ffmpeg-devel@ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH v5 08/12]
> avfilter/overlay_graphicsubs: Add overlay_graphicsubs and
> graphicsub2video filters
> 
> Soft Works:
> > Signed-off-by: softworkz <softworkz@hotmail.com>
> > ---
> >  doc/filters.texi                     | 104 ++++
> >  libavfilter/Makefile                 |   2 +
> >  libavfilter/allfilters.c             |   2 +
> >  libavfilter/vf_overlay_graphicsubs.c | 731
> +++++++++++++++++++++++++++
> >  4 files changed, 839 insertions(+)
> >  create mode 100644 libavfilter/vf_overlay_graphicsubs.c
> >
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index 9ad6031d23..a6da018259 100644
> > --- a/doc/filters.texi
> > +++ b/doc/filters.texi
> > @@ -25016,6 +25016,110 @@ tools.
> >

[..]

> > +
> > +#define OFFSET(x) offsetof(OverlaySubsContext, x)
> > +#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM |
> AV_OPT_FLAG_FILTERING_PARAM)
> > +
> > +static const AVOption overlay_graphicsubs_options[] = {
> > +    { "x", "set the x expression", OFFSET(x_expr),
> AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
> > +    { "y", "set the y expression", OFFSET(y_expr),
> AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
> > +    { "eof_action", "Action to take when encountering EOF from
> secondary input ",
> > +        OFFSET(fs.opt_eof_action), AV_OPT_TYPE_INT, { .i64 =
> EOF_ACTION_REPEAT },
> > +        EOF_ACTION_REPEAT, EOF_ACTION_PASS, .flags = FLAGS,
> "eof_action" },
> > +        { "repeat", "Repeat the previous frame.",   0,
> AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_REPEAT }, .flags = FLAGS,
> "eof_action" },
> > +        { "endall", "End both streams.",            0,
> AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_ENDALL }, .flags = FLAGS,
> "eof_action" },
> > +        { "pass",   "Pass through the main input.", 0,
> AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS },   .flags = FLAGS,
> "eof_action" },
> > +    { "eval", "specify when to evaluate expressions",
> OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_FRAME}, 0,
> EVAL_MODE_NB-1, FLAGS, "eval" },
> > +         { "init",  "eval expressions once during initialization",
> 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit =
> "eval" },
> > +         { "frame", "eval expressions per-frame",
> 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit =
> "eval" },
> > +    { "shortest", "force termination when the shortest input
> terminates", OFFSET(fs.opt_shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 },
> 0, 1, FLAGS },
> > +    { "repeatlast", "repeat overlay of the last overlay frame",
> OFFSET(fs.opt_repeatlast), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },
> 
> Why are you duplicating framesync options? They are already
> accessible
> (that's what the preinit and the child_next/child_class_next stuff is
> for).

Both vf_overlay and vf_overlay_qsv have it that way, are you sure 
I can drop it?

Thanks,
sw
diff mbox series

Patch

diff --git a/doc/filters.texi b/doc/filters.texi
index 9ad6031d23..a6da018259 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -25016,6 +25016,110 @@  tools.
 
 @c man end VIDEO SINKS
 
+@chapter Subtitle Filters
+@c man begin SUBTITLE FILTERS
+
+When you configure your FFmpeg build, you can disable any of the
+existing filters using @code{--disable-filters}.
+
+Below is a description of the currently available subtitle filters.
+
+@section graphicsub2video
+
+Renders graphic subtitles as video frames. 
+
+This filter replaces the previous "sub2video" hack which did the conversion implicitly and up-front as subtitle filtering wasn't possible at that time.
+To retain compatibility with earlier sub2video command lines, this filter is being auto-inserted in those cases.
+
+For overlaying graphicsal subtitles it is recommended to use the 'overlay_graphicsubs' filter which is more efficient and takes less processing resources.
+
+This filter is still useful in cases where the overlay is done with hardware acceleration (e.g. overlay_qsv, overlay_vaapi, overlay_cuda) for preparing the overlay frames.
+
+It accepts the following parameters:
+
+@table @option
+@item size, s
+Set the size of the output video frame.
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Overlay PGS subtitles
+(not recommended - better use overlay_graphicsubs)
+@example
+ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:1]graphicsub2video[subs];[0:0][subs]overlay" output.mp4
+@end example
+
+@item
+Overlay PGS subtitles implicitly 
+The graphicsub2video is inserted automatically for compatibility with legacy command lines. 
+@example
+ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:0][0:1]overlay" output.mp4
+@end example
+@end itemize
+
+@section overlay_graphicsubs
+
+Overlay graphic subtitles onto a video stream.
+
+This filter can blend graphical subtitles on a video stream directly, i.e. without creating full-size alpha images first.
+The blending operation is limited to the area of the subtitle rectangles, which also means that no processing is done at times where no subtitles are to be displayed.
+
+
+It accepts the following parameters:
+
+@table @option
+@item x
+@item y
+Set the expression for the x and y coordinates of the overlaid video
+on the main video. Default value is "0" for both expressions. In case
+the expression is invalid, it is set to a huge value (meaning that the
+overlay will not be displayed within the output visible area).
+
+@item eof_action
+See @ref{framesync}.
+
+@item eval
+Set when the expressions for @option{x}, and @option{y} are evaluated.
+
+It accepts the following values:
+@table @samp
+@item init
+only evaluate expressions once during the filter initialization or
+when a command is processed
+
+@item frame
+evaluate expressions for each incoming frame
+@end table
+
+Default value is @samp{frame}.
+
+@item shortest
+See @ref{framesync}.
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Overlay PGS subtitles
+@example
+ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:1]graphicsub2video[subs];[0:0][subs]overlay" output.mp4
+@end example
+
+@item
+Overlay PGS subtitles implicitly 
+The graphicsub2video is inserted automatically for compatibility with legacy command lines. 
+@example
+ffmpeg -i "https://streams.videolan.org/samples/sub/PGS/Girl_With_The_Dragon_Tattoo_2%3A23%3A56.mkv" -filter_complex "[0:0][0:1]overlay" output.mp4
+@end example
+@end itemize
+@c man end SUBTITLE FILTERS
+
 @chapter Multimedia Filters
 @c man begin MULTIMEDIA FILTERS
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index a510dd12b4..f9b33d4ead 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -289,6 +289,7 @@  OBJS-$(CONFIG_FSPP_FILTER)                   += vf_fspp.o qp_table.o
 OBJS-$(CONFIG_GBLUR_FILTER)                  += vf_gblur.o
 OBJS-$(CONFIG_GEQ_FILTER)                    += vf_geq.o
 OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
+OBJS-$(CONFIG_GRAPHICSUB2VIDEO_FILTER)       += vf_overlay_graphicsubs.o framesync.o
 OBJS-$(CONFIG_GRAPHMONITOR_FILTER)           += f_graphmonitor.o
 OBJS-$(CONFIG_GRAYWORLD_FILTER)              += vf_grayworld.o
 OBJS-$(CONFIG_GREYEDGE_FILTER)               += vf_colorconstancy.o
@@ -362,6 +363,7 @@  OBJS-$(CONFIG_OVERLAY_CUDA_FILTER)           += vf_overlay_cuda.o framesync.o vf
 OBJS-$(CONFIG_OVERLAY_OPENCL_FILTER)         += vf_overlay_opencl.o opencl.o \
                                                 opencl/overlay.o framesync.o
 OBJS-$(CONFIG_OVERLAY_QSV_FILTER)            += vf_overlay_qsv.o framesync.o
+OBJS-$(CONFIG_OVERLAY_GRAPHICSUBS_FILTER)    += vf_overlay_graphicsubs.o framesync.o
 OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o vulkan.o
 OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
 OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index b27ef6f027..ca983db5b4 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -344,6 +344,7 @@  extern const AVFilter ff_vf_oscilloscope;
 extern const AVFilter ff_vf_overlay;
 extern const AVFilter ff_vf_overlay_opencl;
 extern const AVFilter ff_vf_overlay_qsv;
+extern const AVFilter ff_vf_overlay_graphicsubs;
 extern const AVFilter ff_vf_overlay_vulkan;
 extern const AVFilter ff_vf_overlay_cuda;
 extern const AVFilter ff_vf_owdenoise;
@@ -522,6 +523,7 @@  extern const AVFilter ff_avf_showvolume;
 extern const AVFilter ff_avf_showwaves;
 extern const AVFilter ff_avf_showwavespic;
 extern const AVFilter ff_vaf_spectrumsynth;
+extern const AVFilter ff_svf_graphicsub2video;
 
 /* multimedia sources */
 extern const AVFilter ff_avsrc_amovie;
diff --git a/libavfilter/vf_overlay_graphicsubs.c b/libavfilter/vf_overlay_graphicsubs.c
new file mode 100644
index 0000000000..15c07c9bc4
--- /dev/null
+++ b/libavfilter/vf_overlay_graphicsubs.c
@@ -0,0 +1,731 @@ 
+/*
+ * Copyright (c) 2021 softworkz
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * overlay graphical subtitles on top of a video frame
+ */
+
+#include "avfilter.h"
+#include "formats.h"
+#include "libavutil/common.h"
+#include "libavutil/eval.h"
+#include "libavutil/avstring.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "internal.h"
+#include "drawutils.h"
+#include "framesync.h"
+
+#include "libavcodec/avcodec.h"
+
+enum var_name {
+    VAR_MAIN_W,    VAR_MW,
+    VAR_MAIN_H,    VAR_MH,
+    VAR_OVERLAY_W, VAR_OW,
+    VAR_OVERLAY_H, VAR_OH,
+    VAR_HSUB,
+    VAR_VSUB,
+    VAR_X,
+    VAR_Y,
+    VAR_N,
+    VAR_POS,
+    VAR_T,
+    VAR_VARS_NB
+};
+
+typedef struct OverlaySubsContext {
+    const AVClass *class;
+    int x, y;                   ///< position of overlaid picture
+    int w, h;
+    AVFrame *outpicref;
+
+    int main_is_packed_rgb;
+    uint8_t main_rgba_map[4];
+    int main_has_alpha;
+    uint8_t overlay_rgba_map[4];
+    int eval_mode;              ///< EvalMode
+
+    FFFrameSync fs;
+
+    int main_pix_step[4];       ///< steps per pixel for each plane of the main output
+    int hsub, vsub;             ///< chroma subsampling values
+    const AVPixFmtDescriptor *main_desc; ///< format descriptor for main input
+
+    double var_values[VAR_VARS_NB];
+    char *x_expr, *y_expr;
+
+    AVExpr *x_pexpr, *y_pexpr;
+} OverlaySubsContext;
+
+static const char *const var_names[] = {
+    "main_w",    "W", ///< width  of the main    video
+    "main_h",    "H", ///< height of the main    video
+    "overlay_w", "w", ///< width  of the overlay video
+    "overlay_h", "h", ///< height of the overlay video
+    "hsub",
+    "vsub",
+    "x",
+    "y",
+    "n",            ///< number of frame
+    "pos",          ///< position in the file
+    "t",            ///< timestamp expressed in seconds
+    NULL
+};
+
+#define MAIN    0
+#define OVERLAY 1
+
+#define R 0
+#define G 1
+#define B 2
+#define A 3
+
+#define Y 0
+#define U 1
+#define V 2
+
+enum EvalMode {
+    EVAL_MODE_INIT,
+    EVAL_MODE_FRAME,
+    EVAL_MODE_NB
+};
+
+static av_cold void overlay_graphicsubs_uninit(AVFilterContext *ctx)
+{
+    OverlaySubsContext *s = ctx->priv;
+
+    ff_framesync_uninit(&s->fs);
+    av_expr_free(s->x_pexpr); s->x_pexpr = NULL;
+    av_expr_free(s->y_pexpr); s->y_pexpr = NULL;
+}
+
+static inline int normalize_xy(double d, int chroma_sub)
+{
+    if (isnan(d))
+        return INT_MAX;
+    return (int)d & ~((1 << chroma_sub) - 1);
+}
+
+static void eval_expr(AVFilterContext *ctx)
+{
+    OverlaySubsContext *s = ctx->priv;
+
+    s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
+    s->var_values[VAR_Y] = av_expr_eval(s->y_pexpr, s->var_values, NULL);
+    /* It is necessary if x is expressed from y  */
+    s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
+    s->x = normalize_xy(s->var_values[VAR_X], s->hsub);
+    s->y = normalize_xy(s->var_values[VAR_Y], s->vsub);
+}
+
+static int set_expr(AVExpr **pexpr, const char *expr, const char *option, void *log_ctx)
+{
+    int ret;
+    AVExpr *old = NULL;
+
+    if (*pexpr)
+        old = *pexpr;
+    ret = av_expr_parse(pexpr, expr, var_names,
+                        NULL, NULL, NULL, NULL, 0, log_ctx);
+    if (ret < 0) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Error when evaluating the expression '%s' for %s\n",
+               expr, option);
+        *pexpr = old;
+        return ret;
+    }
+
+    av_expr_free(old);
+    return 0;
+}
+
+static int overlay_graphicsubs_query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats;
+    AVFilterLink *inlink0 = ctx->inputs[0];
+    AVFilterLink *inlink1 = ctx->inputs[1];
+    AVFilterLink *outlink = ctx->outputs[0];
+    int ret;
+    static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_BITMAP, AV_SUBTITLE_FMT_NONE };
+    static const enum AVPixelFormat supported_pix_fmts[] = {
+        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV444P,
+        AV_PIX_FMT_ARGB,  AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_ABGR,  AV_PIX_FMT_BGRA,
+        AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
+        AV_PIX_FMT_NONE
+    };
+
+    /* set input0 video formats */
+    formats = ff_make_format_list(supported_pix_fmts);
+    if ((ret = ff_formats_ref(formats, &inlink0->outcfg.formats)) < 0)
+        return ret;
+
+    /* set input1 subtitle formats */
+    formats = ff_make_format_list(subtitle_fmts);
+    if ((ret = ff_formats_ref(formats, &inlink1->outcfg.formats)) < 0)
+        return ret;
+
+    /* set output0 video formats */
+    formats = ff_make_format_list(supported_pix_fmts);
+    if ((ret = ff_formats_ref(formats, &outlink->incfg.formats)) < 0)
+        return ret;
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    OverlaySubsContext *s = ctx->priv;
+    int ret;
+
+    if ((ret = ff_framesync_init_dualinput(&s->fs, ctx)) < 0)
+        return ret;
+
+    outlink->w = ctx->inputs[MAIN]->w;
+    outlink->h = ctx->inputs[MAIN]->h;
+    outlink->time_base = ctx->inputs[MAIN]->time_base;
+
+    return ff_framesync_configure(&s->fs);
+}
+
+// divide by 255 and round to nearest
+// apply a fast variant: (X+127)/255 = ((X+127)*257+257)>>16 = ((X+128)*257)>>16
+#define FAST_DIV255(x) ((((x) + 128) * 257) >> 16)
+
+// calculate the non-pre-multiplied alpha, applying the general equation:
+// alpha = alpha_overlay / ( (alpha_main + alpha_overlay) - (alpha_main * alpha_overlay) )
+// (((x) << 16) - ((x) << 9) + (x)) is a faster version of: 255 * 255 * x
+// ((((x) + (y)) << 8) - ((x) + (y)) - (y) * (x)) is a faster version of: 255 * (x + y)
+#define UNPREMULTIPLY_ALPHA(x, y) ((((x) << 16) - ((x) << 9) + (x)) / ((((x) + (y)) << 8) - ((x) + (y)) - (y) * (x)))
+
+/**
+ * Blend image in src to destination buffer dst at position (x, y).
+ */
+static av_always_inline void blend_packed_rgb(const AVFilterContext *ctx,
+    const AVFrame *dst, const AVSubtitleRect *src,
+    int x, int y,
+    int is_straight)
+{
+    OverlaySubsContext *s = ctx->priv;
+    int i, imax, j, jmax;
+    const int src_w = src->w;
+    const int src_h = src->h;
+    const int dst_w = dst->width;
+    const int dst_h = dst->height;
+    uint8_t alpha;          ///< the amount of overlay to blend on to main
+    const int dr = s->main_rgba_map[R];
+    const int dg = s->main_rgba_map[G];
+    const int db = s->main_rgba_map[B];
+    const int da = s->main_rgba_map[A];
+    const int dstep = s->main_pix_step[0];
+    const int sr = s->overlay_rgba_map[R];
+    const int sg = s->overlay_rgba_map[G];
+    const int sb = s->overlay_rgba_map[B];
+    const int sa = s->overlay_rgba_map[A];
+    uint32_t *pal = (uint32_t *)src->data[1];
+    int slice_start, slice_end;
+    uint8_t *S, *sp, *d, *dp;
+
+    i = FFMAX(-y, 0);
+    imax = FFMIN3(-y + dst_h, FFMIN(src_h, dst_h), y + src_h);
+
+    slice_start = i;
+    slice_end = i + imax;
+
+    sp = src->data[0] + slice_start       * src->linesize[0];
+    dp = dst->data[0] + (slice_start + y) * dst->linesize[0];
+
+    for (i = slice_start; i < slice_end; i++) {
+        j = FFMAX(-x, 0);
+        S = sp + j;
+        d = dp + ((x + j) * dstep);
+
+        for (jmax = FFMIN(-x + dst_w, src_w); j < jmax; j++) {
+            uint32_t val = pal[*S];
+            const uint8_t *sval = (uint8_t *)&val;
+            alpha = sval[sa];
+
+            // if the main channel has an alpha channel, alpha has to be calculated
+            // to create an un-premultiplied (straight) alpha value
+            if (s->main_has_alpha && alpha != 0 && alpha != 255) {
+                const uint8_t alpha_d = d[da];
+                alpha = UNPREMULTIPLY_ALPHA(alpha, alpha_d);
+            }
+
+            switch (alpha) {
+            case 0:
+                break;
+            case 255:
+                d[dr] = sval[sr];
+                d[dg] = sval[sg];
+                d[db] = sval[sb];
+                break;
+            default:
+                // main_value = main_value * (1 - alpha) + overlay_value * alpha
+                // since alpha is in the range 0-255, the result must divided by 255
+                d[dr] = is_straight ? FAST_DIV255(d[dr] * (255 - alpha) + sval[sr] * alpha) :
+                        FFMIN(FAST_DIV255(d[dr] * (255 - alpha)) + sval[sr], 255);
+                d[dg] = is_straight ? FAST_DIV255(d[dg] * (255 - alpha) + sval[sg] * alpha) :
+                        FFMIN(FAST_DIV255(d[dg] * (255 - alpha)) + sval[sg], 255);
+                d[db] = is_straight ? FAST_DIV255(d[db] * (255 - alpha) + sval[sb] * alpha) :
+                        FFMIN(FAST_DIV255(d[db] * (255 - alpha)) + sval[sb], 255);
+            }
+
+            if (s->main_has_alpha) {
+                switch (alpha) {
+                case 0:
+                    break;
+                case 255:
+                    d[da] = sval[sa];
+                    break;
+                default:
+                    // apply alpha compositing: main_alpha += (1-main_alpha) * overlay_alpha
+                    d[da] += FAST_DIV255((255 - d[da]) * S[sa]);
+                }
+            }
+            d += dstep;
+            S += 1;
+        }
+        dp += dst->linesize[0];
+        sp += src->linesize[0];
+    }
+}
+
+static av_always_inline void blend_plane_8_8bits(const AVFilterContext *ctx, const AVFrame *dst, const AVSubtitleRect *src,
+    const uint32_t *yuv_pal, int src_w, int src_h, int dst_w, int dst_h, int plane, int hsub, int vsub,
+    int x, int y, int dst_plane, int dst_offset, int dst_step)
+{
+    const int src_wp = AV_CEIL_RSHIFT(src_w, hsub);
+    const int src_hp = AV_CEIL_RSHIFT(src_h, vsub);
+    const int dst_wp = AV_CEIL_RSHIFT(dst_w, hsub);
+    const int dst_hp = AV_CEIL_RSHIFT(dst_h, vsub);
+    const int yp = y >> vsub;
+    const int xp = x >> hsub;
+    uint8_t *s, *sp, *d, *dp, *dap;
+    int imax, i, j, jmax;
+    int slice_start, slice_end;
+
+    i = FFMAX(-yp, 0);                                                                                     \
+    imax = FFMIN3(-yp + dst_hp, FFMIN(src_hp, dst_hp), yp + src_hp);                                       \
+
+    slice_start = i;
+    slice_end = i + imax;
+
+    sp = src->data[0] + (slice_start << vsub) * src->linesize[0];
+    dp = dst->data[dst_plane] + (yp + slice_start) * dst->linesize[dst_plane] + dst_offset;
+
+    dap = dst->data[3] + ((yp + slice_start) << vsub) * dst->linesize[3];
+
+    for (i = slice_start; i < slice_end; i++) {
+        j = FFMAX(-xp, 0);
+        d = dp + (xp + j) * dst_step;
+        s = sp + (j << hsub);
+        jmax = FFMIN(-xp + dst_wp, src_wp);    
+
+        for (; j < jmax; j++) {
+            uint32_t val = yuv_pal[*s];
+            const uint8_t *sval = (uint8_t *)&val;
+            const int alpha = sval[3];
+            const int max = 255, mid = 128;
+            const int d_int = *d;
+            const int sval_int = sval[plane];
+
+            switch (alpha) {
+            case 0:
+                break;
+            case 255:
+                *d = sval[plane];
+                break;
+            default:
+                if (plane > 0)
+                    *d = av_clip(FAST_DIV255((d_int - mid) * (max - alpha) + (sval_int - mid) * alpha) , -mid, mid) + mid;
+                else
+                    *d = FAST_DIV255(d_int * (max - alpha) + sval_int * alpha);
+                break;
+            }
+
+            d += dst_step;
+            s += 1 << hsub;
+        }
+        dp += dst->linesize[dst_plane];
+        sp +=  (1 << vsub) * src->linesize[0];
+        dap += (1 << vsub) * dst->linesize[3];
+    }
+}
+
+#define RGB2Y(r, g, b) (uint8_t)(((66 * (r) + 129 * (g) +  25 * (b) + 128) >> 8) +  16)
+#define RGB2U(r, g, b) (uint8_t)(((-38 * (r) - 74 * (g) + 112 * (b) + 128) >> 8) + 128)
+#define RGB2V(r, g, b) (uint8_t)(((112 * (r) - 94 * (g) -  18 * (b) + 128) >> 8) + 128)
+/* Converts R8 G8 B8 color to YUV. */
+static av_always_inline void rgb_2_yuv(uint8_t r, uint8_t g, uint8_t b, uint8_t* y, uint8_t* u, uint8_t* v)
+{
+    *y = RGB2Y((int)r, (int)g, (int)b);
+    *u = RGB2U((int)r, (int)g, (int)b);
+    *v = RGB2V((int)r, (int)g, (int)b);
+}
+
+
+static av_always_inline void blend_yuv_8_8bits(AVFilterContext *ctx, AVFrame *dst, const AVSubtitleRect *src, int hsub, int vsub, int x, int y)
+{
+    OverlaySubsContext *s = ctx->priv;
+    const int src_w = src->w;
+    const int src_h = src->h;
+    const int dst_w = dst->width;
+    const int dst_h = dst->height;
+    const int sr = s->overlay_rgba_map[R];
+    const int sg = s->overlay_rgba_map[G];
+    const int sb = s->overlay_rgba_map[B];
+    const int sa = s->overlay_rgba_map[A];
+    uint32_t *pal = (uint32_t *)src->data[1];
+    uint32_t yuvpal[256];
+
+    for (int i = 0; i < 256; ++i) {
+        const uint8_t *rgba = (uint8_t *)&pal[i];
+        uint8_t *yuva = (uint8_t *)&yuvpal[i];
+        rgb_2_yuv(rgba[sr], rgba[sg], rgba[sb], &yuva[Y], &yuva[U], &yuva[V]);
+        yuva[3] = rgba[sa];
+    }
+
+    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, Y, 0,    0,    x, y, s->main_desc->comp[Y].plane, s->main_desc->comp[Y].offset, s->main_desc->comp[Y].step);
+    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, U, hsub, vsub, x, y, s->main_desc->comp[U].plane, s->main_desc->comp[U].offset, s->main_desc->comp[U].step);
+    blend_plane_8_8bits(ctx, dst, src, yuvpal, src_w, src_h, dst_w, dst_h, V, hsub, vsub, x, y, s->main_desc->comp[V].plane, s->main_desc->comp[V].offset, s->main_desc->comp[V].step);
+}
+
+static int config_input_main(AVFilterLink *inlink)
+{
+    int ret;
+    AVFilterContext *ctx  = inlink->dst;
+    OverlaySubsContext *s = inlink->dst->priv;
+    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
+
+    av_image_fill_max_pixsteps(s->main_pix_step,    NULL, pix_desc);
+    ff_fill_rgba_map(s->overlay_rgba_map, AV_PIX_FMT_RGB32); // it's actually AV_PIX_FMT_PAL8);
+
+    s->hsub = pix_desc->log2_chroma_w;
+    s->vsub = pix_desc->log2_chroma_h;
+
+    s->main_desc = pix_desc;
+
+    s->main_is_packed_rgb = ff_fill_rgba_map(s->main_rgba_map, inlink->format) >= 0;
+    s->main_has_alpha = !(pix_desc->flags & AV_PIX_FMT_FLAG_ALPHA);
+
+    /* Finish the configuration by evaluating the expressions
+       now when both inputs are configured. */
+    s->var_values[VAR_MAIN_W   ] = s->var_values[VAR_MW] = ctx->inputs[MAIN   ]->w;
+    s->var_values[VAR_MAIN_H   ] = s->var_values[VAR_MH] = ctx->inputs[MAIN   ]->h;
+    s->var_values[VAR_OVERLAY_W] = s->var_values[VAR_OW] = ctx->inputs[OVERLAY]->w;
+    s->var_values[VAR_OVERLAY_H] = s->var_values[VAR_OH] = ctx->inputs[OVERLAY]->h;
+    s->var_values[VAR_HSUB]  = 1<<pix_desc->log2_chroma_w;
+    s->var_values[VAR_VSUB]  = 1<<pix_desc->log2_chroma_h;
+    s->var_values[VAR_X]     = NAN;
+    s->var_values[VAR_Y]     = NAN;
+    s->var_values[VAR_N]     = 0;
+    s->var_values[VAR_T]     = NAN;
+    s->var_values[VAR_POS]   = NAN;
+
+    if ((ret = set_expr(&s->x_pexpr,      s->x_expr,      "x",      ctx)) < 0 ||
+        (ret = set_expr(&s->y_pexpr,      s->y_expr,      "y",      ctx)) < 0)
+        return ret;
+
+    if (s->eval_mode == EVAL_MODE_INIT) {
+        eval_expr(ctx);
+        av_log(ctx, AV_LOG_VERBOSE, "x:%f xi:%d y:%f yi:%d\n",
+               s->var_values[VAR_X], s->x,
+               s->var_values[VAR_Y], s->y);
+    }
+
+    av_log(ctx, AV_LOG_VERBOSE,
+           "main w:%d h:%d fmt:%s overlay w:%d h:%d fmt:%s\n",
+           ctx->inputs[MAIN]->w, ctx->inputs[MAIN]->h,
+           av_get_pix_fmt_name(ctx->inputs[MAIN]->format),
+           ctx->inputs[OVERLAY]->w, ctx->inputs[OVERLAY]->h,
+           av_get_pix_fmt_name(ctx->inputs[OVERLAY]->format));
+    return 0;
+}
+
+static int do_blend(FFFrameSync *fs)
+{
+    AVFilterContext *ctx = fs->parent;
+    AVFrame *mainpic, *second;
+    OverlaySubsContext *s = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    unsigned num_rects, i;
+    int ret;
+
+    ret = ff_framesync_dualinput_get_writable(fs, &mainpic, &second);
+    if (ret < 0)
+        return ret;
+    if (!second)
+        return ff_filter_frame(ctx->outputs[0], mainpic);
+
+    if (s->eval_mode == EVAL_MODE_FRAME) {
+        int64_t pos = mainpic->pkt_pos;
+
+        s->var_values[VAR_N] = inlink->frame_count_out;
+        s->var_values[VAR_T] = mainpic->pts == AV_NOPTS_VALUE ?
+            NAN : mainpic->pts * av_q2d(inlink->time_base);
+        s->var_values[VAR_POS] = pos == -1 ? NAN : pos;
+
+        s->var_values[VAR_OVERLAY_W] = s->var_values[VAR_OW] = second->width;
+        s->var_values[VAR_OVERLAY_H] = s->var_values[VAR_OH] = second->height;
+        s->var_values[VAR_MAIN_W   ] = s->var_values[VAR_MW] = mainpic->width;
+        s->var_values[VAR_MAIN_H   ] = s->var_values[VAR_MH] = mainpic->height;
+
+        eval_expr(ctx);
+        av_log(ctx, AV_LOG_DEBUG, "n:%f t:%f pos:%f x:%f xi:%d y:%f yi:%d\n",
+               s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
+               s->var_values[VAR_X], s->x,
+               s->var_values[VAR_Y], s->y);
+    }
+
+    num_rects = second->num_subtitle_rects > 1 ? 1 : second->num_subtitle_rects;
+
+    for (i = 0; i < num_rects; i++) {
+        const AVSubtitleRect  *sub_rect = second->subtitle_rects[i];
+
+        if (sub_rect->type != AV_SUBTITLE_FMT_BITMAP) {
+            av_log(NULL, AV_LOG_WARNING, "sub2video: non-bitmap subtitle\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        switch (inlink->format) {
+        case AV_PIX_FMT_YUV420P:
+            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 1, 1, sub_rect->x + s->x, sub_rect->y + s->y);
+            break;
+        case AV_PIX_FMT_YUV422P:
+            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 1, 0, sub_rect->x + s->x, sub_rect->y + s->y);
+            break;
+        case AV_PIX_FMT_YUV444P:
+            blend_yuv_8_8bits(ctx, mainpic, sub_rect, 0, 0, sub_rect->x + s->x, sub_rect->y + s->y);
+            break;
+        case AV_PIX_FMT_RGB24:
+        case AV_PIX_FMT_BGR24:
+        case AV_PIX_FMT_ARGB:
+        case AV_PIX_FMT_RGBA:
+        case AV_PIX_FMT_BGRA:
+        case AV_PIX_FMT_ABGR:
+            blend_packed_rgb(ctx, mainpic, sub_rect, sub_rect->x + s->x, sub_rect->y + s->y, 1);
+            break;
+        default:
+            av_assert0(0);
+            break;
+        }
+    }
+
+    return ff_filter_frame(ctx->outputs[0], mainpic);
+}
+
+static av_cold int overlay_graphicsubs_init(AVFilterContext *ctx)
+{
+    OverlaySubsContext *s = ctx->priv;
+
+    s->fs.on_event = do_blend;
+    return 0;
+}
+
+static int overlay_graphicsubs_activate(AVFilterContext *ctx)
+{
+    OverlaySubsContext *s = ctx->priv;
+    return ff_framesync_activate(&s->fs);
+}
+
+static int graphicsub2video_query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats;
+    AVFilterLink *inlink = ctx->inputs[0];
+    AVFilterLink *outlink = ctx->outputs[0];
+    static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_BITMAP, AV_SUBTITLE_FMT_NONE };
+    static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_RGB32, AV_PIX_FMT_NONE };
+    int ret;
+
+    /* set input subtitle formats */
+    formats = ff_make_format_list(subtitle_fmts);
+    if ((ret = ff_formats_ref(formats, &inlink->outcfg.formats)) < 0)
+        return ret;
+
+    /* set output video formats */
+    formats = ff_make_format_list(pix_fmts);
+    if ((ret = ff_formats_ref(formats, &outlink->incfg.formats)) < 0)
+        return ret;
+
+    return 0;
+}
+
+static int graphicsub2video_config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    OverlaySubsContext *s = ctx->priv;
+
+    if (s->w <= 0 || s->h <= 0) {
+        s->w = inlink->w;
+        s->h = inlink->h;
+    }
+    return 0;
+}
+
+static int graphicsub2video_config_output(AVFilterLink *outlink)
+{
+    const AVFilterContext *ctx  = outlink->src;
+    OverlaySubsContext *s = ctx->priv;
+    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(outlink->format);
+
+    outlink->w = s->w;
+    outlink->h = s->h;
+    outlink->sample_aspect_ratio = (AVRational){1,1};
+
+    av_image_fill_max_pixsteps(s->main_pix_step, NULL, pix_desc);
+    ff_fill_rgba_map(s->overlay_rgba_map, AV_PIX_FMT_RGB32);
+
+    s->hsub = pix_desc->log2_chroma_w;
+    s->vsub = pix_desc->log2_chroma_h;
+
+    s->main_desc = pix_desc;
+
+    s->main_is_packed_rgb = ff_fill_rgba_map(s->main_rgba_map, outlink->format) >= 0;
+    s->main_has_alpha = !(pix_desc->flags & AV_PIX_FMT_FLAG_ALPHA);
+
+    return 0;
+}
+
+static int graphicsub2video_filter_frame(AVFilterLink *inlink, AVFrame *src_frame)
+{
+    AVFilterLink *outlink = inlink->dst->outputs[0];
+    AVFrame *out;
+    const unsigned num_rects = src_frame->num_subtitle_rects;
+    unsigned int i;
+
+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!out)
+        return AVERROR(ENOMEM);
+
+    memset(out->data[0], 0, out->linesize[0] * out->height);
+
+    out->pts = src_frame->pts;
+
+
+    for (i = 0; i < num_rects; i++) {
+        const AVSubtitleRect  *sub_rect = src_frame->subtitle_rects[i];
+
+        if (sub_rect->type != AV_SUBTITLE_FMT_BITMAP) {
+            av_log(NULL, AV_LOG_WARNING, "sub2video: non-bitmap subtitle\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        blend_packed_rgb(inlink->dst, out, sub_rect, sub_rect->x, sub_rect->y, 1);
+    }
+
+    av_frame_free(&src_frame);
+    return ff_filter_frame(outlink, out);
+}
+
+#define OFFSET(x) offsetof(OverlaySubsContext, x)
+#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
+
+static const AVOption overlay_graphicsubs_options[] = {
+    { "x", "set the x expression", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
+    { "y", "set the y expression", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, FLAGS },
+    { "eof_action", "Action to take when encountering EOF from secondary input ",
+        OFFSET(fs.opt_eof_action), AV_OPT_TYPE_INT, { .i64 = EOF_ACTION_REPEAT },
+        EOF_ACTION_REPEAT, EOF_ACTION_PASS, .flags = FLAGS, "eof_action" },
+        { "repeat", "Repeat the previous frame.",   0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_REPEAT }, .flags = FLAGS, "eof_action" },
+        { "endall", "End both streams.",            0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_ENDALL }, .flags = FLAGS, "eof_action" },
+        { "pass",   "Pass through the main input.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS },   .flags = FLAGS, "eof_action" },
+    { "eval", "specify when to evaluate expressions", OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_FRAME}, 0, EVAL_MODE_NB-1, FLAGS, "eval" },
+         { "init",  "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit = "eval" },
+         { "frame", "eval expressions per-frame",                  0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },
+    { "shortest", "force termination when the shortest input terminates", OFFSET(fs.opt_shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+    { "repeatlast", "repeat overlay of the last overlay frame", OFFSET(fs.opt_repeatlast), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },
+    { NULL }
+};
+
+static const AVOption graphicsub2video_options[] = {
+    { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, FLAGS },
+    { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, FLAGS },
+    { NULL }
+};
+
+FRAMESYNC_DEFINE_CLASS(overlay_graphicsubs, OverlaySubsContext, fs);
+
+static const AVFilterPad overlay_graphicsubs_inputs[] = {
+    {
+        .name         = "main",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input_main,
+        .flags        = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
+    },
+    {
+        .name         = "overlay",
+        .type         = AVMEDIA_TYPE_SUBTITLE,
+    },
+};
+
+static const AVFilterPad overlay_graphicsubs_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_output,
+    },
+};
+
+const AVFilter ff_vf_overlay_graphicsubs = {
+    .name          = "overlay_graphicsubs",
+    .description   = NULL_IF_CONFIG_SMALL("Overlay graphical subtitles on top of the input."),
+    .preinit       = overlay_graphicsubs_framesync_preinit,
+    .init          = overlay_graphicsubs_init,
+    .uninit        = overlay_graphicsubs_uninit,
+    .priv_size     = sizeof(OverlaySubsContext),
+    .priv_class    = &overlay_graphicsubs_class,
+    .query_formats = overlay_graphicsubs_query_formats,
+    .activate      = overlay_graphicsubs_activate,
+    FILTER_INPUTS(overlay_graphicsubs_inputs),
+    FILTER_OUTPUTS(overlay_graphicsubs_outputs),
+};
+
+AVFILTER_DEFINE_CLASS(graphicsub2video);
+
+static const AVFilterPad graphicsub2video_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_SUBTITLE,
+        .filter_frame = graphicsub2video_filter_frame,
+        .config_props = graphicsub2video_config_input,
+    },
+};
+
+static const AVFilterPad graphicsub2video_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = graphicsub2video_config_output,
+    },
+};
+
+AVFilter ff_svf_graphicsub2video = {
+    .name          = "graphicsub2video",
+    .description   = NULL_IF_CONFIG_SMALL("Convert graphical subtitles to video"),
+    .query_formats = graphicsub2video_query_formats,
+    .priv_size     = sizeof(OverlaySubsContext),
+    .priv_class    = &graphicsub2video_class,
+    FILTER_INPUTS(graphicsub2video_inputs),
+    FILTER_OUTPUTS(graphicsub2video_outputs),
+};